Railway signal and/or point control equipment



May 13, 1941. .1. B. GRIFFITHs E-r AL 22415906 RAILWAY SIGNAL AND/0R POINT CONTROL EQUIPMENT Filed May 21, 1938 14 Sheets-Sheet 2 May 13, 1941.

J. B. GRIFFI'rHs Erm. 2,241,906

RAILWAY SIGNAL AND/OR POINT CONTROL EQUIIMENT` Filed May 21, 1938 14 Sheets-Sheet 5 May 13, 1941.

J. B. GRIFFITHS l-ITALl Filed May 2l, 1938 14 Sheets-Sheet 4 F/GJ A TTQP/VE y May 13, 1941.` J. B. GRIFFITHs ETAL RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT 14 Sheets-Sheet 5.

Filed May 21, '1938 May 13, 1941.

RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT Filed May 21, 19323 14 Sheets-Sheet 6 May 13, 1941. .1. B. GRIFFITHS E-l-.AL

14 Sheets-Sheet 7 Filed May 21, 1938 May 13, 1941. J. B. GRIFFITHs ETAL RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT Filed May 21, 195s 14 sheets-sheet s' May 13, 1941'. .1. BQ'GRIFFITHS ETAL 2,241,906

RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT Filed May 21, 1938 14 Sheets-Sheet 9 May 13, 1941. 1. B. GRIFFITHS Erm. 2,241,906 v RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT Anne/v;

MY 13 1941- J. B. GRIFFITHS ETAL 2,241,906

RAILWAY SIGNAL AND/0R POINT CONTROL EQUIPMENT Filed May 2l, 1938 14 Sheets-Sheet l1 BY TTOPIVLC;

May 13, 1941.

J. B. GRIFFITHS ETAL vRAILWAY SIGNAL AND/0R POINT CONTROL EQUIPMENT Filed May 2l, 1938 14 Sheets-Sheet 12 F/G/ZA.

May 13, 1941'. J. B. GRiFr-'ITHS Erm. 2,241,905

l RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT TTOF/VEY J. B. GRIFFITHS ETAI.l

May 13, 1941.

l RAILWAY SIGNAL AND/0R POINT coNTRoL EQUIPMENT Filed May 21, 1938 '1.4 sheets-sheet 14 1 P 4 .Nfv hay,

Anne/v5 Patented May'lS, 1941 UNITED STA'iir-i gist RAILWAY SIGNAL AND/OR POINT CONTROL EQUIPMENT John Balmain Griffiths and Andrew Brown,

London, England, assignors to International Standard Electric Corporation,

New York,

Application May '21, 1938, Serial No. y209,1918 In Great Britain May 31, 1937 10 Claims. (C1. 246-134) directly concerned in setting up the route are in such positions that no other conflicting route is simultaneously set up and freed, and that no other possible source of interference or trouble exists.

For this purpose it is present practice to provide large numbers of massive relays each controlling a multiple contact spring pile-up. Complex checking circuits are formed via the relay contacts and each of these circuits may comprise contacts of many relays if the signal and point switch system to be controlled is in any Way complex.

The present invention relates to control equipment of the kind in which a multi-position switch device is used to control the setting up of a group of inter-related routes, each switch being essentially unable to set up more than one route at a time, as it is physically unable to be in more than one position at the same time. It is, of course, impossible, in many instances, to select groups of routes, that is, of signals and switch points, entirely unrelated to other routes, and the setting up of routes in certain positions of one control switch may therefore be dependent on ther setting of another control switch or switches. The switches used are preferably sequence switches of the type used in the Rotary System of Automatic Telephony. The well known sequence switch is of the general type illustrated in the patent to Reynolds 1,127,808, February 9, 1915, and may consist of a plurality of discs or cams rotatable with a driving spindle and cooperating brushes. The discs or cams may be of metal separated by insulation, the metal parts being cut away in part so that in certain 'positions the brushes associated with a particular disc do not close a circuit. The switch spindle is rotated to a number of positions corresponding to desired settings and in each position will complete selected ones of the circuits associated therewith. In the preferred arrangement each switch is provided with a magnetically controlled clutch for coupling the spindle to a motor for securing the desired drive. Wiper switches of telephone type may also be used but it is to be understood that the actual switches although operating in the same way as the telephone switches may be of more robust design in keeping with railway switching practice.

The invention will be clearly understood from the following description of two embodiments of the invention shown in the accompanying drawings, in which:

Figs. 1 and 1A arranged together show the layout of the' tracks over which pass twenty routes to be. controlled;

Fig. 2 shows the twenty different through and shunting routes which can be set up;

Fig. 3 shows the positions of ve sequence switches S/S in which the different routes are set up and the interlocking necessary between the sequence switches;

Figs. 4 and 4A together show a table giving full information regarding the routes and their relation to the other routes, the track circuits, signals, and switch points;

Figs. 5 and 5A together show a table giving similar information regarding the points;

Figs. 6 and 7, of which Fig. 7 should be placed below Fig. 6, show the control circuits of sequence switch No. I and its associated relays;

Figs, 8 and 8A, with 8A placed below 8 show the switch points operating and locking circuits;

Figs. 9 and 9A together show the running signal operating circuits;

Figs. 10 and 10A together show the shunt signal operating circuits;

Fig. 11 shows the track stick relays and their circuits;

Figs. 12 and 12A together show the switch points control and detection circuits for points No. 5B. Similar circuits are provided for points 5I, 52, 53 and 5i;

Fig. 13 shows a modified form of the circuit shown in Fig, 6 by means of which the circuit of Fig. 6 is simplified.

As far as possible the symbols for written circuits" in accordance with British Standards Specication 376-2 have been used.

A brief explanation of the conventions used in the circuit diagrams will serve to simplify a following of the description. Because of the complexity of the circuit simple diagrams using straight lines are used where possible to facilitate a following of the system. The contacts controlled by the various relays are shown by open arrow heads, those above the line indicating front contacts and those below the line indicating back contacts, those contacting the line indicating that the contacts are normally closed and those spaced therefrom indicating the contacts are normally open. The relay armatures are separated from the relays in order not to unduly complicate the following of the circuit and are generally designated by small letters corresponding to the upper case letter designating the corresponding relay.

The five sequence switches are designated by numbers I, 2, 3, 4 and 5, the switch cams by a letter following the number as 2A, and the contacts at which the cam closes are designated by numerals following the letter associated with the brush indication where several brushes are shown. Y

Referring to Fig. 6, IB is a cam B on sequence switch I, the right hand top contact shown as an outline triangle touching the cam represents a wiper making continuous contact with the cam, while the left hand vbottom contact represents a wiper making continuous contact with the cam from position I8 to position 2. If the left hand bottom contact represented a wiper making contact in positions I8, I, 2, but not between positions, it would have been numbered I8.I.2.

The connections between cams IB, IC, ID represent connections between the cams by brass separators whereby these cams are connected The cam IA I-I is the positioning cam which is cut so that the switch can stop' in every position I-I8, but not between positions.

Figs. 1 andA 1A show a length of railroad including four tracks via which seventeen different routes I-IB, 2li may be set up by means of switch points 50, 54. The routes are traced via the track sections TC, for each of these routes as shown in Fig. 2. Route numbers Il, I8, I9 are left spare for additions to shunting routes.

Fig. 3 shows in column 2 the sequence switch which controls the setting of the route given in column I, andcolumn 3 shows the position of the sequence switch allocated tothe route in question..v The interlocking columns RI to R5 show the positions of the four sequence switches other than that controlling the route in question'which are allocated to routes which conilict with the route in question and for which therefore interlocking between the sequence switches is necessary. Thus interlocking must be provided to prevent switch R3 taking up position I if R! is in position I, 2, 3 or 4, or R2 is in position 2, 3 or 4. Route l is given a sequence switch to itself although it might be entirely relay controlled. Route 'I can only be set up if I2 or VI3 is rst set up and conflicts with exactly the same routes as l2 and I 3. Therefore route I can only be set up if switch I is in position 5 or 6 and the interlocking between switch I and switches 2, 3 and 4 obviates interlocking between switch 5 and switches 2, 3 and 4.

Figs. 4 and LA give further information regarding the routes. In column 2 are Igiven routes by which the route in column I is freed or released. Thus route I is freed by route I2 or I3 as stated above. Column 3 states that the setting up of the route in column I frees the route in column 3 for setting purposes.

Column 4 gives conflicting routes including i those on the same sequence switch.

Columns 5 and 6 T. C. controls show the` track circuit conditions which must obtain before theroute in question can be set up.

v1t will be seen that route 3 has two alternative sets of track circuit conditions. The main set of conditions is for the regular signal, but signal 3 also has a call-on lamp CO for passing an engine, for instance, waiting in TG2, to a train standing in TCS. For lighting the call-on lamp the subsidiary conditions apply. This will be seen later with regard to SHR and 3 COI-IR in Fig. 9.

Columns 7 and 8 Detection show the switch points positions which must obtain before the route can be set up, N being the normal through position and R the reverse or switching position.

Columns 9 and Io Backlocking give respectively the routes, occupation of which prevent release of the route in question, and the routes, occupation of which allows the route to be released. The bracket in column 9 relating to route 2 means that occupation of TCS is a factor only when switch points 5I are in normal position. When operated in column 9 with respect to routes 8 and I4 means that the route cannot be released while the. sequence switchris olf-normal, there being no track relays for sidings SI, S2.

Column I!V relates to control of signal aspect by the aspect of signals ahead. Thus for signal yI to show green, signal 2 must show yellow or green.

Figs. 5 and 5A show the control arrangements for the points switch mechanisms.

Column 2 gives the track circuits occupation of which prevents operation of the switch points. With regard to points switch 50, the condition of track circuit H33 is a factor only when signal 20 is reversed, that is, is at yellow or green. With regard to switch points 53 track circuit Ill2 is always y a factor, but if it remains occupied for more than a specified time period, automatic time release means removes the lock as it means that a train is standing still or moving very slowly in TCIBZ and the switch points can be safely changed.

Column 3 gives the manual route switch positions in which the switch points are reversed. The statement N restored points in regard to each set of switch points means that the switch points are arranged to restore automatically to normal when a route is restored. This is because only the middle two tracks are running routes.

Columns 4 and 5 show the positions of the' manual route switches which lock the switch points in reverse and normal positions respeco tively, while column 6 shows the intercontrol benecessary interlocking by this method since ocv casions frequently arise when, for example, two routes A and B which do not interlock with each other, both interlock with a third route C. It will be clear that the routes A and B cannot be carried on the same rotary switch since they may require to be set up simultaneously, while the route C may be controlled from the same switch as either A or B. If route C is allocated to the switch controlling A, then electrical interlocking between the two switches will be necessary to provide the interlocking between routes B and C.

It will be seen by comparison of the interlocking columns of Fig. 3 with column 4 of Fig. 4, that all the routes which have been allocated to any one sequence switch are required to interlock with each other, and that in addition to this, certain routes which cannot be placed under con-trol of the same sequence switch are electrically interlocked. This means that certain interlocking is required between the various switches in specified positions.

For example, route which has been allocated to positionV I on sequence switch No. 1 is shown on the interlocking table to lock with routes I, 3, 6, 8, 9, IIJ, II, I2, I3, I4, I5, I6 and 2ll. Of these routes 6, I0, II, I2, I3, I4 and 20 are automatically interlocked with 5 by virtue of their being on the same sequence switch and electrical interlocking is, therefore, only required with the remaining routes. As a result, sequence switch No. 1 in `position I must be interlocked with switch No. 2 in positions 3 and 4 (for routes I5 and I6), switch 3 in positions I and 2 (for routes I and 3), and switch 4 in positions I and 2 (for routes 8 and 9).

The circuit by which this interlocking is actually obtained is shown in Figs. 6 and 7 for sequence switch No. 1. Each sequence switch clutch armature controls contacts CC in such a way that a relay such as IRC is energised while the clutch is in normal position, and that a relay such as IRF is energised While the clutch is energised and the switch is moving.

Let us consider the effect of the signalman operating the panel control key for route 5. Assuming that the No. 1 switch is in the home position I8, the circuit will be completed for the clutch magnet of this switch as follows:

From battery feed BI, over contacts of cam F of switch No. 3 provided that this switch is not in positions I or 2, cam F on switch No, 4 provided that this switch is not in positions I or 2, cam D of switch 2 provided that this switch is not in positions 3 or 4, contacts of the manual route switch for route 5 reversed, cam B of switch No. 1 in position I8, front relay contacts I of relays IZR, 2RC, SRC, and 4R0, clutch magnet coil IR, winding of motor start relay MS, to negative.

The operation of the motor start relay MS starts up the main driving shaft and the operation of the No. l clutch magnet will cause the No. 1 sequence switch to be rotated until the circuit above described is broken by the cam IB moving out of position I8. The No, 1 switch will then drive on to position I under control of the cam IA over the obvious circuit shown in the upper line of Fig. 6. It will be seen, therefore, that in response to the operation of rou-te switch No. 5, sequence switch No. 1 moves into position i provided that the position already occupied by switches 2, 3 and 4 makes route 5 obtainable in accordance with the original interlocking chart.

rIhe contacts I of relays ERC, 3RC and 4RC, are included in the circuit above described in order that the No. 1 switch will not nd a driving circuit in the event of one of the switches 2, 3 and 4 actually being in motion. This provision is necessary to cover the possibility of a moving switch, which is not in a conflicting position at the instant of test, subsequently stopping in a conicting position. The contacts I of IZR are included to prevent a switch already stationary in one route position being moved on to another route position by the operation of a second panel key. It will be seen that relay I ZR is operated on one winding via cam H of switch I when the switch is at home and thereafter locks over contacts IZR/2 to the main driving circuit for the clutch magnet, so that when the switch moves out of position I8, the relay IZR will remain operated until that switch comes to rest in the chosen route position, whereupon relay IZR will be released and cannot subsequently operate until the switch returns to its home position. Any further operation of route switches will be ineffective in driving this sequence switch since opening the contacts IZR/ I breaks the common feed from all such circuits.

The only circuit by means of which the clutch magnet can be energised to restore lthe switch to its home position is over contacts IYR/I, the relay IYR (Fig. 7) being operated in conjunction with the back locking requirements as described later.

Having operated the sequence switch to lthe desired route position, it is necessary to prove that this is actually a correct and safe route before operating any switch points or signals. To obtain this proof relay IPR is included. Contacts of this relay are used in conjunction with the sequence switch cams for the actual setting up of the desired route.

When the sequence switch No. 1 is in position I it will be seen that the relay PR can only be operated if the switches 2, 3 and 4, remain in positions which do not conflict with route No. 5 and if the panel control key No. 5 remains in the reverse position. In other words, the relay PR operates if, and only if, the present position of the corresponding sequence switch agrees with the setting of the control panel and, furthermore, is safe in relation to the other sequence switches. The circuit for IPR is via front contacts IRC/I, contacts of cam F of sequence switch I in position I, reversed contacts of manual route switch 5, cam D of switch 2, cam F of switch 4, cam F of switch 3, to BI. Relay IPR operates its re peater relay IQR by closing contacts IPR.

Having positioned the sequence switch I and operated the proving relay IPR it is possible for one of the other sequence switches to drive to a non-conicting position, but, before reaching that non-conicting position, it may pass momentarily through a coniiicting position. It is undesirable that this momentary condition, which in any case cannot set up the conflicting route, should be permitted to interrupt the circuit of the PR relay which might have the effect of unnecessarily flashing the danger signal in the face of approaching traffic and, therefore, in cases where a sequence switch carries conflicting as well as non-conflicting routes, the interlocking contacts are by-passed by contacts of the corresponding relay RF which are closed while the switch is actually in motion. As previously explained relay IRF is operated all the time the sequence switch clutch is in the energised -or driving position just as relay IRC is operated while the clutch is in its normal position. For instance, in the circuit which we have just described, switch No. 2 conflicts with route 5 in positions 3 and 4 but not in positions I and 2, so that cams 2D and ZI are shunted out by contacts of the relay ZRF while switch No. 2 is in motion.

It will be appreciated that if the switch 2 is moving and cam D thereof is shunted by 2RF/I, contacts 2RC/I will be open and therefore the circuit of IR is never closed while cam D is shunted.

Having positioned the sequence switch in accordance with the desired route and, furthermore, having checked the vaccuracy of this positioning, it is now necessary to operate the relevant switch points to set the track for the desired route.

The switch point lock circuits are Vshown in Fig. 8. Each set of switch points is provided with a normal lock relay NLR and a reverse lock relay RLR which, in turn, control the actual switch point motors, such as SPM, Fig. 12.

Fig. 8 shows the contacts of an individual switch point control key, e. g. 50 N. C. R. associated with each set of switch points in addition to the circuit for controlling the points in accordance with route setting. These switch point control keys have three Ypositions N, C, R. When a switch point control key is set to normal N the normal switch point lock relay NLR will immediately be operated unless a route has previously been set upwhich requires those switch points to be reversed or, alternatively, unless certain track sections are occupied which prohibit the movement of the switch points. Similarly, when the switch point control key is set to reverse R the reverse lock relay RLR will be operated unless the reverse position of the switch points is inadmissible. When the point control key is set toits 'central position C then either the normal lockk relay NLR or the reverse lock relay RLR may be operated in accordance with the setting of vari-ous sequence switches.

'I'hese switch point control switches would generally be left in the central position so that all possible train movements are at the disposal of the route contro-l switches and the individual switch point switches would only be used in cases of emergency.

Let us consider the setting up of route No. 5 the relevant switch point switches being in the central position and sequence switch No. 1 having been driven to position I as described above.

Referring back to Figs. 1 and 2, route 5 involves a movement from TC. |05 across switch points 5i] and 5I to TC. 6 and so necessitates the reversing of switch points 50 and 5I.

The only routes requiring reversal of switch points 5i? are 5, 6, Irand II to which positions I- of sequence switch I, .are allocated. The normal lock relay NLR energizes via 50N or energised, cam il of switch I in positions 5/I8 only or back contact 3' of relay IPR, and normally closed front contacts IlSTR/Z, IIiTR/, STR/2 of the corresponding track relays.

When route 5 is set up on sequence switch I and IPR is energised, SBNLR is released, assuming that switch points 59 are in normal position and relays NLR Fig. l and NKR, Fig. 12 are operated, by the opening of the contacts of cam I0 and of contacts IPR/3 Fig. 8.

Relay 50RLR operates via 5to operated contacts IPR/I, contacts I/l and 9/1 of cam IP, back contacts 59NLR/3, cam contacts 5F, and 3K both in normal position I8, front contacts 53NLR/ I proving that points 53 are in normal position, and front contacts IQSTR/Z, IDllIR/, STR/2 proving that track circuits m3, IM, 3 are unoccupied. Switch points motor 50PM, Fig. 12 is now operated'to reverse the switch points; BI'I, front contacts fRLR/Z, back contacts 50RKR/4, 59PM, back contacts RKR/l, and front contacts 5GRLR/5, N. Relay 5NKR, Fig. 12 is released, when the switch points leave normal, and relay 50RKR is operated when the reverse position is reached. Relay RLR is maintained operated via its holding circuit via front contacts ilRLR/I, and back contacts ElRKR/B' until the switch' points are fully reversed, when SQRKR opens the holding .circuit of SBRLR and stops the motor.

Similarly, when switch No. 1 moves into positionk I, relay 5INLR is de-energised and BIRLR operated over contacts STR/3, ETR/2, cam L on switch 3 in position I8, front contacts SZNLR/I, back contacts 5INLR/3, cam R on switch I in position 'I, front contacts IPR/2 contacts of the switch point switch 5I in the central position, winding of EiRLR, to negative.

It will be seen that the various track relay and switch point lock relay contacts included in the circuits for SilRLR and EIRLR correspond to the switch point locking chart shown in Fig. 5.

All the switch points shown in this particular lay-out happen to be normally restored switch points, i. e., points which return to normal unless they are deiinitely reversed either by the setting up or a route which 'requires the switch points to be reversed or by the operation of the individual pointJ control key. Thus, in the case of switch points Et, as soon as sequence switch No. I is restored to normal or is moved out of positions I to t (all of which require switch points 5i) reversed) relay ESRLR will be released and illNL-R immediately reoperated provided that the indivi-dual switch point; control switch for switch points 5) is either in the central or the normal position and, also, that none of the tracks 3, |04, and |93 is occupied.

If any of these tracks are occupied, then a movement of the switch points 50 in either direction is prohibited.

A holding circuit for the various switch point lock relays is provided so that When a movement of switch points isv once commenced it must be completed before `any opposite movement of the same points can take place. Thus, in the case of relay ilRLR, when this relay is operated it locks as described above over contacts RLR/I 'and iRKR/S so that even if the operating circuit is broken during the travel time of the switch points, the reverse lock relay will remain energised until the reverse movement of switch points has been completed and detected whereupon the reverse switch point detector relay RKR will break the holding circuit just described and permit the switch points to be returned to normal if desired. This holding circuit is necessary to obviate the possibility of switch points being left in an intermediate position.

A similar circuit is, of course, provided for the normal lock relay so that, once a movement from reverse to normal is commenced, it must be completed.

Having described the method by which points 59 and '5l are reversed in order to set up route No. 5 let us now consider the operation of the relevant shunt signal 5/6/1, shown in Fig. 10.

When sequence switch No. I is in position I, the relay .i/E/'lI-IR will be operated from the battery feed over back contacts SRKR/ I, front contacts ENLR/, front IQR/E (arepeatvoi IPR), back contacts 5iRKR/2, front contact 52NKR/2, back contact EERLR/, frontcontacts ElNLR/l, cam T of switch I in .position I, winding of B/S/l-IR to negative.

The operation of relay FUE/'IHR will illuminate the oblique pair of lamps on the position light signal shown in the right-hand bottom corner of Fig. 10. This signal thus displays proceed aspect to the driver of a train standing on TC.IIJ5

respond to the circuit described for /I/lI-IRV above with the additional fact that certain track relay and track holding relay contacts are included in the circuit.

For example, in order to clear the running signal No. I it is necessary to drive sequence switch No. 3 to position I and to prove that points 50 and 5I are both normal.

On reference to the interlocking table we find that it is also necessary to prove that track circuits 3, 4, and 'I are clear. Therefore, the operating circuit for the relay IHR shown in 9 is as follows: From battery feed, front cont-acts 3PR/2, front contacts 35E/2, back contacts |!RLR/4, front contacts NKR/I, cam 0 of sequence switch 3 in position I, front contacts 5INKR/ I, back contacts 5iRLR/4, front contacts ITB/5, and front contacts 'ISR/2. The relay IHR when operated removes the feed from the red aspect lamp IRE and illuminates either the green lamp IDE or the yellow lamp II-IE in accordance with the condition of the running signal No. 2 ahead, as shown by the position of the contacts 2ER/2.

It will be noted that contacts of the relays SSR, and 'ISR were included in the circuit for the relay IHR in place of the corresponding track relay contacts.

These SR, or holding relays, are shown in Fig. l1 and their function is to register the occupation of a particular track circuit in order that a release condition which depends on the track circuit having been occupied will still be available even if the track circuit in question is no longer occupied at the time when the release condition is utilised.

For example, the relay BSR is normally held operated over its own front contact SSR/I and the contact STR/ 5 of the No. 3 track relay. On the occupation of No. 3 track, this circuit will be broken down; thereafter, the relay BSR can only be re-operated when No. 3 track is again clear and, in addition, sequence switch No. 3 is in its home position and sequence switch No. I is in some position other than I, 2, 3 or 4.

Before track 3 was originally occupied one of the routes I, 3, 5, 6, I0 or II must have been cleared and the positions of the sequence switches I and 3 included in the circuit for 3SR prove that these signals giving access to track 3 have been restored to danger.

It will be seen from the interlocking table that the routes I, 3, 5, 6, I0 and I I all have theirback locking released by track circuit 3 occupied. This means in effect that, even if .the relevant approach tracks are still occupied, the signal may be restored to danger provided that track No. 3 has .been occupied. It is clear that the signalman may not restore the route while track 3 is still occupied; therefore, the holding relay SSR. is included, vso that he can restore the route any time after track 3 becomes unoccupied. As soon as the route in question has been restored, the holding relay 3SR will be re-operated and the yback locking will once more be effective.

Similar holding relay circuits are provided for the other tracks 5, 1, |03 and `|04, which are required to release back locking of any routes.

Fig. 11 also shows the circuit for the time release relay 5'3JR which is required for the control of switch points 53 in conjunction with track circuit IU2. The purpose of this control is to prevent movement of switch points y53 when a through tra-in is passing rapidly over track |02 towards switch points 53 but to permit a movement of these points in the event of a train having been stationary on track vH12 for a specified time-say one minute.

As soon as track |02 is occupied the thermoelement JRA is yenergised and, after it has been heated for the specified time, contacts JRA/ I will close and operate relay 53JR, which locks over front contacts 53JR/3 as long as track |02 remains occupied and disconnects the thermo-element JRA at back contacts 53/JR/3.

Referring once more to the switch point'lock circuits, Fig. 8, it will be seen that the control circuit for relays ESNLR and ESRLR are both interrupted by the release of IZTR but may be re-made after, say, one minute over contacts 53JR/I.

Consider now the effect of restoring manual route switch No. 5 to normal.

As soon as the route switch moves out of the reverse position the proving circuit of relay IIPR, Fig. 6, Will be interrupted at 5R. Relays IPR, IQR will release and No. 5 signal control relay E//THR, Fig. 10, will also be released.

The circuit is then provided yfor relay -IYR over cam I of the No. 1 sequence switch in position yI, No. 5 manual route switch normal, back contacts 4 of relay S/B/I-IR normal, front contacts I of the track relays IMTR and |015/ IllTR showing track clear, vand the front contacts IRC/2 indicating that the sequence switch is actually at rest in position I. The track relays N35/|06 and |04 are included in the back locking circuit as prescribed by the interlocking table and, furthermore, in the event of track circuit No. 3 having been occupied the relay SSR. will be released and its back contacts 3 will provide a circuit for IYR independently of the occupation of tracks l/I and |04. When the relay IYR is operated it locks over cam IK and front contacts IYR/.2 until the switch leaves position I'I. Contacts IYR/I provide a circuit for the clutch magnet and motor start relay until the switch leaves position I'I when it will be driven into position I'8 under control of its A cam. Similar circuits will be provided for the control of all the Iother sequence switches in accor-dance with the interlocking and back locking specified.

lInstead of sequence switches, wiper switches can be used, the route control circuits for the different routes being formed via wipers of the switch and the bank contacts in the different positions of the switch allocated to the routes.

The purpose of the modification of Fig. 6 shown in Fig. 13 is to reduce as far as possible the number of relays and/ or relay contacts which are required to be associated with each sequence switch. This reduct-ion in relays is effected by reduction in the number of RC contacts and by elimination of RF relays.

In Fig. 6 the current for energising the sequence switch clutch magnet is taken from the contacts 2 RC.I, 3 RCA and 4 RCJ before being fed lto the clutch magnet. These contacts are included to prove that switches 2, 3 and `i are stationary, before permitting switch I to move,

and so long Vas the contacts areplaced in Vthis posi-tion a separate set` of contacts covering all switches which carry-conilicting routes must be included Vin the control circuit of each clu'tch magnet.V Y

In Fig. 13 the RC contacts are shown on the common side of the clutch magnet and .by this means the same contacts may be used in the control circuits of other clutch magnets, for example, if switch No. 2 carries routes which conflict with some of vthe routes carried Aby switches 3 and 4, then the control circuit for the No. `2

clutch could be connected through the point marked Bf so thatcontacts .3 RC and 4 RC would serve both clutches I and 2. It is estimated that on a large interlocking system, application of this principle would reduce the number rof RC contacts required .to about one quarter of lthe number required in the arrangev ment shown in Fig. 6.

Fig. 6 shows contacts of the relay 2 RF bridging the interlocking cams of sequence switch No.

. 2 in the ycontrol circuit. These contacts were included .to prevent Vmomentary interruption of the proving relay circuit, while switch No. 2, in driving .to a position which did not conflict with that occupied by No. y1, might pass through a 1Vposition'which did con-iiict with that -occupied YbyNo. 1.

ping in a conicting position, -evenyif such Ystoppage is -due toa fault cond-ition.

In order to hold relay PR operated while a Vswitch is'passing through two or moresuccessive 'coniicting positions, it is desirable-to complete "the circuit through the switch cams while the rswitch is'passing through the intervening posi- `tionbetween route positions, thus the'cam V2D associated with routeV which was originally cuit interruption extending from positions li/lrwould be Yrep-laced by two interrupt-ions from 273/4/371/4 and 33h/31A respectively.

This modification does not imposeany serious Y timing difficulty on relay PR and in addition to the lelimination ofY several RF relays, Yprovides the 'advantagethat'the vital interlocking cam contacts are not vbridged by any relay contacts,

"wiring etc., theshortV circuiting of which might be dangerous.

Many cases arise in practice of a set of Vsiding switch points and signals, ior instance, which are changed at infrequent intervals but for which a signal box is provided, the majority of the work at the signal box being to'act as a tandem repeater for messages between busy signal boxes on either side. Y

Considerable economies could be achieved in systems mainly provided with local control, if

lcontrol of infrequently operated switch points and signals were placed in the hands of adjacent main signal boxes. j Y

It is now proposed to use control signals `for instancarof the known constant total code type wherein each code'` signal comprises the same number .of impulses which together total a constant sum, Veach characteristic of a complete set *of conditions .tojbe set up Aat a remotely-controlled setv ofV l*signals and -switch points, Vto set Ycontrol switches of the kind described above.

The proper reception of a constant total code signal-correct number of digits and correct total num-ber of impulses-checks that no error has occurred in transmission. v

The new set of conditions would be set up in response to a correctly received code and a simple signal would be sent back to inform the signalman that the code sent had been correctly received.

Alternatively an answering constant-total code signal would be returned to the control cabin on correct receipt of a setting signal, said answering signal being individual to the particular setting signal received. In this case, the setting up of the route at the controlled position would not take place until the signalman, on receipt of the check code signal, sent an operating signal.

This system may be used in conjunction with a centralised trafiic indicator system such as that described in British Patent Specification No. 461,136 which is arranged to test the position of all equipment on a length of track at frequent intervals and to change the setting of an indicator at the control cabin accordingly. The change in the setting of the signals and points in response to a constant-total code setting signal would be indicated in a short time on the indicator board.

This system of remote control and indication, besides being applicable to the circumstances detailed above, is also capable of use for the remote control of a number of spaced sets of switch points and signals in tandem, rfor instance, by using a preliminary constant-total code signal characteristic of the set to be controlled.

What is claimed is:

1. In a railway signal and switch points control system wherein the track system involves tracks which may be set to selectively control a, number of conflicting routes, an arrangement for assuring coniiictingroutes are not simultaneously set up comprising, aY plurality of rotary control switches each control `switch comprising a number of switch elements fixed on a common shaft, contacts operatively associated with each switch element in different angular positions thereof to effect closure of route setting circuits to provide interlocking between said route setting circuits associated with each switch to avoid setting up of conflicting routes, means interconnecting contacts of certain of said rotary ele-v ments on oneof said rotary control switches` with contacts on another of said rotary switches for providing a further interlock ybetween said rotary switches to avoid setting up of other coniiicting routes, a plurality of manually adjustable route switches, means responsive to operation of said route switches to selected route position vto initiate operation of said control switches yinto .the position indicated by said adjustment, means responsive to the conditionl that said selected vrouteis not free of conflicts with other selected routes for preventing operation of said control switch and means operated Vwith saidsystem to prevent completion of a route settingcircuit in response'to the stopping of a control switch :in route setting position if the setting of saidcontrol vswitch disagrees .with-.the setting of the -manual route switch in response vto vwhicll'operation-of said control switch' was initiated.

2. In a railway signal and switch points control system, accordingl'to `claim 1,' anarrangement further comprising'guard devicesforpre-y 

